Replace footer links and fix broken links

doc/integration/elasticsearch.md

 # Elasticsearch integration **[STARTER ONLY]**
 
-> [Introduced][ee-109] in GitLab [Starter][ee] 8.4. Support
-> for [Amazon Elasticsearch][aws-elastic] was [introduced][ee-1305] in GitLab
-> [Starter][ee] 9.0.
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/109 "Elasticsearch Merge Request") in GitLab [Starter](https://about.gitlab.com/pricing/) 8.4. Support
+> for [Amazon Elasticsearch](http://docs.aws.amazon.com/elasticsearch-service/latest/developerguide/es-gsg.html) was [introduced](https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1305) in GitLab
+> [Starter](https://about.gitlab.com/pricing/) 9.0.
 
 This document describes how to set up Elasticsearch with GitLab. Once enabled,
 you'll have the benefit of fast search response times and the advantage of two
@@ -27,12 +27,12 @@ GitLab from source. Providing detailed information on installing Elasticsearch
 is out of the scope of this document.
 
 Once the data is added to the database or repository and [Elasticsearch is
-enabled in the admin area](#enable-elasticsearch) the search index will be
+enabled in the admin area](#enabling-elasticsearch) the search index will be
 updated automatically. Elasticsearch can be installed on the same machine as
-GitLab, or on a separate server, or you can use the [Amazon Elasticsearch][aws-elastic]
+GitLab, or on a separate server, or you can use the [Amazon Elasticsearch](http://docs.aws.amazon.com/elasticsearch-service/latest/developerguide/es-gsg.html)
 service.
 
-You can follow the steps as described in the [official web site][install] or
+You can follow the steps as described in the [official web site](https://www.elastic.co/guide/en/elasticsearch/reference/current/_installation.html "Elasticsearch installation documentation") or
 use the packages that are available for your OS.
 
 ## Elasticsearch repository indexer (beta)
@@ -117,7 +117,7 @@ The following Elasticsearch settings are available:
 | `Use the new repository indexer (beta)` | Perform repository indexing using [GitLab Elasticsearch Indexer](https://gitlab.com/gitlab-org/gitlab-elasticsearch-indexer). |
 | `Search with Elasticsearch enabled` | Enables/disables using Elasticsearch in search. |
 | `URL`                              | The URL to use for connecting to Elasticsearch. Use a comma-separated list to support clustering (e.g., "http://host1, https://host2:9200"). If your Elasticsearch instance is password protected, pass the `username:password` in the URL (e.g., `http://<username>:<password>@<elastic_host>:9200/`). |
-| `Using AWS hosted Elasticsearch with IAM credentials` | Sign your Elasticsearch requests using [AWS IAM authorization][aws-iam] or [AWS EC2 Instance Profile Credentials][aws-instance-profile]. The policies must be configured to allow `es:*` actions. |
+| `Using AWS hosted Elasticsearch with IAM credentials` | Sign your Elasticsearch requests using [AWS IAM authorization](http://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_access-keys.html) or [AWS EC2 Instance Profile Credentials](http://docs.aws.amazon.com/codedeploy/latest/userguide/getting-started-create-iam-instance-profile.html#getting-started-create-iam-instance-profile-cli). The policies must be configured to allow `es:*` actions. |
 | `AWS Region` | The AWS region your Elasticsearch service is located in. |
 | `AWS Access Key` | The AWS access key. |
 | `AWS Secret Access Key` | The AWS secret access key. |
@@ -351,7 +351,7 @@ Here are some common pitfalls and how to overcome them:
 
 - **I indexed all the repositories but I can't find anything**
 
-    Make sure you indexed all the database data [as stated above](#adding-gitlab-data-to-the-elasticsearch-index).
+    Make sure you indexed all the database data [as stated above](#adding-gitlabs-data-to-the-elasticsearch-index).
 
 - **I indexed all the repositories but then switched elastic search servers and now I can't find anything**
 
@@ -381,7 +381,7 @@ Here are some common pitfalls and how to overcome them:
 
 - Exception `Elasticsearch::Transport::Transport::Errors::BadRequest`
 
-    If you have this exception (just like in the case above but the actual message is different) please check if you have the correct Elasticsearch version and you met the other [requirements](#requirements).
+    If you have this exception (just like in the case above but the actual message is different) please check if you have the correct Elasticsearch version and you met the other [requirements](#system-requirements).
     There is also an easy way to check it automatically with `sudo gitlab-rake gitlab:check` command.
 
 - Exception `Elasticsearch::Transport::Transport::Errors::RequestEntityTooLarge`
@@ -399,15 +399,3 @@ Here are some common pitfalls and how to overcome them:
     for this setting ("Maximum Size of HTTP Request Payloads"), based on the size of
     the underlying instance.
 
-[ee-1305]: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1305
-[aws-elastic]: http://docs.aws.amazon.com/elasticsearch-service/latest/developerguide/es-gsg.html
-[aws-iam]: http://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_access-keys.html
-[aws-instance-profile]: http://docs.aws.amazon.com/codedeploy/latest/userguide/getting-started-create-iam-instance-profile.html#getting-started-create-iam-instance-profile-cli
-[ee-109]: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/109 "Elasticsearch Merge Request"
-[elasticsearch]: https://www.elastic.co/products/elasticsearch "Elasticsearch website"
-[install]: https://www.elastic.co/guide/en/elasticsearch/reference/current/_installation.html "Elasticsearch installation documentation"
-[pkg]: https://about.gitlab.com/downloads/ "Download Omnibus GitLab"
-[elastic-settings]: https://www.elastic.co/guide/en/elasticsearch/reference/current/setup-configuration.html#settings "Elasticsearch configuration settings"
-[ee]: https://about.gitlab.com/pricing/
-[force-merge]: https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-forcemerge.html "Force Merge"
-[lucene-handling-of-deleted-documents]: https://www.elastic.co/blog/lucenes-handling-of-deleted-documents "Lucene's Handling of Deleted Documents"